How did An Essay on Blindness anticipate Louis Braille’s method of reading by touch?

In his 1749 work Lettre sur les aveugles (An Essay on Blindness), French philosopher Denis Diderot proposed that the sense of touch could be effectively honed to allow blind individuals to read. By emphasizing that sensory experience—rather than sight—was the primary vehicle for understanding and reasoning, Diderot provided a philosophical foundation for the education of the blind.12

His essay anticipated the 19th-century Braille system by arguing that blind persons could be educated if instruction focused on their existing skills rather than their lack of sight. Diderot’s ideas were further informed by his observations of individuals like the musician Melanie de Salignac, who had already devised a tactile method for reading music and corresponding with others. These insights into the potential for tactile literacy directly foreshadowed the methods Louis Braille would later develop and refine into a standardized system of reading and writing for the sightless.12